Desmid
of the month
March 2006

Euastrum
humerosum

Like Euastrum oblongumEuastrum humerosum belongs to the group of Euastrum species in which the median apical incurvation is in the form of a deep,
closed invagination. Semicells are about pyramidal in outline with rather
deep incurvations separating apical, lateral and basal lobes. The basal
lobes in their turn are incurved too, so more or less doubled. In the
Netherlands both the nominate variety and var. affine (characterized
by deeper lateral incurvations) are of occasional occurrence in acidic,
oligotrophic moorland pools.